60 GHz wireless communications belongs to a category of millimeter wave communications. A millimeter wave (Millimeter Wave) refers to an electromagnetic wave whose frequency ranges from 300 GHz to 30 GHz. A wavelength of the millimeter wave is from 1 mm to 10 mm, and therefore it is referred to as the millimeter wave. The millimeter wave has been widely applied in many fields, such as communications, radar, navigation, remote sensing, and radio astronomy. As an important branch of millimeter wave communications, 60 GHz communications mainly has advantages such as a large channel capacity, excellent directivity, high confidentiality, and favorable international versatility. A 60 GHz wireless communications technology can provide transmission at a multi-gigabit rate, and support high-definition video transmission, fast synchronization, a wireless USB, and a high speed wireless local area network.
In a 60 GHz wireless communications system, by using a directional multi-gigabit (DMG) Beacon frame or an Announce frame, a personal basic service set (PBSS) control point (PBSS Control Point, PCP) or an access point (AP) provides a PBSS or a basic service set (BSS) with basic timing and services of allocating channel access periods such as an SP and a contention-based access period (CBAP). As a network controller, the PCP or the AP needs to perform scheduling to avoid interference when allocating the SP and the CBAP in a data transfer interval (DTI). Because a directional transmission technology of beamforming is adopted, the 60 GHz communications standard 802.11ad allows different allocated SPs to overlap. Overlapping SPs may improve spatial sharing and spatial multiplexing in the BSS.
A STA may request the PCP or the AP to reserve an exclusive channel access period SP. Because of a dynamic feature of a variable rate of a streaming service, the SP may be surplus or insufficient, which can be resolved by adopting a method for dynamically truncating the SP or dynamically extending the SP respectively. To implement dynamic truncation of the SP, in the prior art, the PCP or the AP indicates, to the STA, whether the SP can be truncated, and if the SP can be truncated, the STA performs an operation of truncating the SP when the SP is surplus. Two manners are available for truncating the SP. In a first manner, the STA first releases remaining time of the SP to the PCP or the AP for subsequent dynamic allocation by the PCP or the AP; in a second manner, the STA directly releases the remaining time of the SP as a CBAP in a broadcasting manner.
However, in the prior art, the PCP or the AP only specifies whether the SP can be truncated, but a manner adopted to truncate the SP is actively determined by the STA, owner of the SP. Consequently, a problem may occur that interference is imposed on an adjacent STA when the STA actively releases the SP in a form of a CBAP.